It is known to store data on different server means in a decentralized manner, and to allow a number of users access to the data stored decentralized. Usually, the users access the data stored in the server means via a client means. In a company's internal computer network, which may comprise a number of server means, access permits are granted to the users, which allow the users to access data stored in the server means. This type of access on the data or the installing of corresponding access permits, however, is only then convenient as long as the client means via which a user accesses the data is a component of the company's internal computer network.
It is desirable to allow a user access to data, which are stored in server means, which belong to different computer networks, as for example, of different companies.
In order to achieve this, in prior art it is necessary that each company has to grant the corresponding access permits for an external user, and has to provide the user with corresponding access data, as login and password. A user may then log into a computer network of a company, and after a successful log in, access data for which the user has the required access permit.
For the access data of another company, it is, however, necessary that the user also logs into the computer network of the other company. According to prior art, it is also necessary that a user, in case he/she wants to access computer networks of different companies, has to log into each computer network separately. This procedure is, on the one hand, inconvenient for the user, because he/she has to log into or register with each computer network separately. On the other hand, for each computer network, the user is provided with own access data, involving for the user an increased effort for the management of the access data. Moreover, the user has to ensure that the access data to the different computer networks are kept safe in order to avoid misuse.
A further disadvantage is that a user, if he/she has logged into computer networks of different companies, may access the data in the respective computer networks. However, he/she is only able to view the data of a single company. A uniform view on all data of all companies, into which the user has logged into thereby, however, is not possible.
US 2012/0150843 A1 tries to solve this problem. US 2012/0150843 A1 teaches a method according to which a user may register with several networks in order to access data of these networks. Thereby, an identifier usable across domains (or usable across servers) is generated by an ID-Association-server for a user, which is assigned to one or more user specific identifiers. By means of the user specific identifiers, a user may log into a certain network. Data relevant to safety of the user (e.g., credit card information) is managed by the ID-Association-server such that this data does not have or is not able to be managed by the network. Thereby, it should be ensured that several networks are able to exchange data (e.g., transaction data) of a user amongst each other without the safety relevant data being able to be exchanged.
Thereby, however, the problem is not solved that a user has to log into several networks, if he/she wants to access several networks simultaneously or in parallel. He/she has to log into each network separately and individually. Also, thereby the problem is not solved that the user is provided with a uniform view on the data from different networks. The data of a network has to be requested separately from the data of another network, and is provided to the user independently of each other.